Method and apparatus for managing wireless communication network radio resources

ABSTRACT

A method and apparatus for managing radio resources in one or more wireless communication networks. At least one radio resource manager (RRM) is provided within a network node, or as an independent entity. The RRM monitors performance on wireless communication links of the network(s) and interacts with nodes associated with those links to change the configuration on a particular wireless communication link if its performance (i.e., quality) falls below an established threshold. Information regarding current resource usage of the network is sent to the RRM by the nodes. Each of the nodes may send a quality report to the RRM including wireless communication link quality measurements and performance statistics. Alternatively, the RRM may perform the wireless communication link quality measurements. The RRM facilitates the broadcasting of information regarding current resource usage of one network to other networks to avoid collisions and interference.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 60/626,979 filed Nov. 10, 2004, which is incorporated byreference as if fully set forth.

FIELD OF INVENTION

The present invention relates to wireless communication networks. Moreparticularly, the present invention relates to a method and apparatusfor managing radio resources in one or more wireless communicationnetworks.

BACKGROUND

A wireless access network comprises a plurality of nodes, such as accesspoints (APs), (i.e., base stations), access routers and wirelesstransmit/receive unit (WTRU). The nodes are connected to each other toestablish a backhaul network. Traffic which originates from or isdestined to the network is routed through the backhaul network.

The backhaul network may be established with wireless communicationlinks. Establishing a backhaul network with wireless communication linkshas advantages over a wired backhaul network, such as ease ofdeployment, low cost and flexibility to implement future changes.

In a wireless backhaul network, interference from other co-deployednetworks not only affects the radio links between the nodes and WTRUsoperating in the affected region, but also the links between the networknodes.

A mesh network is a network comprising a plurality of nodes, each ofwhich is connected to at least one neighboring node such that trafficmay be routed via one or more hops through the network. In the meshnetwork, a degradation of the link throughput between two nodes iscarefully observed for routing purposes, since the throughput on acritical link could affect the overall performance of the network. Thedegradation can be caused by several factors, such as an increase ininterference. As the degradation exceeds a certain level, an alternativerouting path is allocated through the mesh network. The time-varying anddynamic nature of the mesh network topology makes it necessary to takeinterference into account beyond initial deployment.

For example, if a wireless backhaul network is deployed next to anexisting wireless network, additional interference generated by thesubsequent network can bring down some of the links in the existingnetwork. This is a potential problem, especially in public bands such asthe 2.4 GHz industrial, scientific and medical (ISM) band with scarcefrequency channels.

When two mesh networks are operating simultaneously in the sameproximity, one or more of the nodes of a first mesh network may roamclose to a second mesh network. This may cause interruption or severeinterference to the second mesh network. This is especially problematicwith radio equipment having relaxed adjacent channel protection andreceiver sensitivity requirements. Therefore, there is a need fordynamic radio resource management and access coordination for the radioaccess network.

SUMMARY

The present invention relates to a method and apparatus for managingradio resources in one or more wireless communication networks. At leastone radio resource manager (RRM) is provided within a network node, oras an independent entity. The RRM monitors performance on wirelesscommunication links of the network(s) and interacts with nodesassociated with those links to change the configuration on a particularwireless communication link if its performance (i.e., quality) fallsbelow an established threshold. Information regarding current resourceusage of the network is sent to the RRM by the nodes. Each of the nodesmay send a quality report to the RRM including wireless communicationlink quality measurements and performance statistics. Alternatively, theRRM may perform the wireless communication link quality measurements.The RRM facilitates the broadcasting of information regarding currentresource usage of one network to other networks to avoid collisions andinterference.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding of the invention may be had from thefollowing description of a preferred embodiment, given by way of exampleand to be understood in conjunction with the accompanying drawingwherein:

FIG. 1 shows an exemplary point-to-multipoint (PtMP) backhaul networkincluding an RRM in accordance with one embodiment of the presentinvention; and

FIG. 2 shows a wireless communication system including a plurality ofnetworks including a mesh network and an RRM operating in accordancewith another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereafter, the terminology “WTRU” includes but is not limited to a userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, or any other type of device capable of operating in a wirelessenvironment. When referred to hereafter, the terminology “node” includesbut is not limited to a Node-B, a base station, an AP, a mesh point(MP), a site controller or any other type of interfacing device in awireless environment.

The present invention is applicable to any type of wirelesscommunication systems including, but not limited to, IEEE 802.11, IEEE802.15 and IEEE 802.16 networks.

In accordance with the present invention, a backhaul network isestablished with wireless communication links. The backhaul network maybe deployed with point-to-point (PtP), PtMP or mesh topologies.Mixed-mode access networks, (e.g., IEEE 802.16 backhaul network to serveIEEE 802.11 APs), and redundant and re-configurable networkfunctionalities are also supported.

FIG. 1 shows an exemplary PtMP backhaul network 100 operating inaccordance with one embodiment of the present invention. The backhaulnetwork 100 includes a plurality of APs 102 ₁-102 _(n), an RRM 106 andat least one WTRU 108. The RRM 106 may reside in any node in the network100, or be configured as a separate, independent entity. In FIG. 1, theRRM 106 is shown as being located in an access router (AR) 104 whichprovides access to an access network 110, such as the Internet. The RRM106 monitors the quality of wireless backhaul links 112 ₁-112 _(n)between respective ones of the APs 102 ₁-102 _(n) and the AR 104. TheAPs 102 ₁-102 _(n) may generate channel quality reports associated withwireless backhaul links 112 ₁-112 _(n) which are received by the RRM106, and/or the RRM 106 may perform quality measurements on the wirelessbackhaul links 112 ₁-112 _(n). The quality reports include measurementsand performance statistics. The performance may be evaluated with anymetrics including, but not limited to, throughput, signal power, a blockerror rate, a bit error rate, a signal-to-interference ratio (SIR) orthe like. The RRM 106 monitors performance on the wireless communicationlinks 112 ₁-112 _(n) in the backhaul network 100.

If the RRM 106 observes performance of a particular wireless backhaullink 112 ₁-112 _(n) drops below a threshold, the RRM 106 dynamicallyinteracts with other nodes in the backhaul network 100 to recover theperformance. For example, the RRM 106 may change the operating frequencyof the wireless communication link 112 ₁. If the backhaul network 100operates in time division multiple access (TDMA), the RRM 106 may assignand reassign timeslots as a function of interference observed inparticular timeslots. If the performance degradation is caused byanother network using frequency hopping which is concurrently deployedin the vicinity of the network 100, the RRM 106 may change its frequencyhopping pattern to minimize mutual interference.

When the RRM 106 recognizes that a WTRU 108 is interfering with awireless backhaul link 112 between an AP 102 and the AR 104, the RRM 106interacts with the AP 102 to mitigate the impact of the interferencecaused by the WTRU 108. For example, the RRM 106 may change operatingfrequency or other parameters on the wireless backhaul link 112 betweenthe AR 104 and the AP 102.

FIG. 2 shows a wireless communication system 150 including a pluralityof networks 200, 300, 400 including at least one mesh network 200 and anRRM 500 operating in accordance with another embodiment of the presentinvention. The mesh network 200 includes a plurality of mesh points(MPs) 202 ₁-202 _(n). Each MP 202 ₁-202 _(n) is wirelessly connected toat least one neighboring MP such that traffic may be routed via one ormore hops through the network 200. The RRM 500 monitors performance onthe wireless communication links 212 ₁-212 _(n) in the mesh network 200and dynamically changes operating frequency or other parameters on thewireless communication links 212 _(i)-212 _(n) between the MPs 202 ₁-202_(n). For example, if the RRM 500 recognizes performance degradation ina particular link 212 ₁-212 _(n), the RRM entity may make measurementsto find an alternative frequency with lower interference and forwardsthis information to relevant ones of the MPs 202 ₁-202 _(n) to changethe operating frequency for the link 212 ₁-212 _(n).

If the RRM 500 observes sudden traffic load increase between two MPs 212₁-212 _(n), the RRM 500 may change a routing algorithm to use twodifferent frequency channels or links, instead of just using one betweenthese two MPs 212 ₁-212 _(n) to accommodate the increased traffic or maychange the backhaul route through an alternative path in the meshnetwork.

In accordance the present invention, the RRM 500 coordinates multiplenetworks 200, 300, 400 such that when two or more networks 200, 300, 400are deployed concurrently in the same proximity, similar rules can beapplied. For example, the RRM 500 receives broadcast information aboutcurrent resource usage of nodes in the network 400, for instance on abroadcast channel (BCH) in the wireless backhaul. Thus, another networkaccesses the information when it starts up in the same proximity andconfigures its parameters appropriately to avoid collision with thenetwork 400.

As shown in FIG. 2, the RRM 500 is in control of networks 200 and 300,but has no control over network 400. However, all broadcast informationreceived from the network 400, (e.g., beacons), may be heard by a nodein networks 200 and 300 and then forwarded to the RRM 500, (and thebroadcast information can be heard by the RRM 500 itself, if it is aWTRU). Then, the RRM 500 would determine whether to take an action overat least one of networks 200 and 300. Thus, a high quantity ofinformation is broadcast on the clear, (i.e., “active channel set” inbeacon messages), and although a node is not part of the network thatbroadcasts the information, such information may be monitored to makebetter RRM decisions. Also, if the RRM 500 is in charge of more than onenetwork, it can apply the same scheme to the other networks.

The broadcast information includes, but is not limited to, a timestampreference, a service indicator, a load indicator, point coordinationfunction (PCF) polling frequency, frequency channels in use, frequencyhopping patterns or frequency assignment patterns and power settings.The broadcast of resource usage allows a concurrent network co-existingin the same proximity to schedule around it. The network may simplychoose a different frequency channel to operate on.

The RRM 500 may configure one or many of the MPs 202 ₁-202 _(n) in themesh network 200 to broadcast the information in regular time intervals,or only when polled, or may send a unicast signaling message whenrequested or in an unsolicited manner to other nodes.

The coordination performed by the RRM may be performed in time domain,such as point coordination function (PCF)-based or hybrid coordinationfunction (HCF)-based IEEE 802.11e extensions. For example, when firstand second networks located in the same proximity have a contention freeperiod starting at substantially the same point in time, the firstnetwork may allow the second network to initiate a polling procedurewhile the first network remains silent. When the second network finisheswith all of its traffic, the first network may start to poll while thesecond network remains silent.

For example, the first network may poll its WTRUs every even 100 msecintervals, (e.g., 0 msec, 200 msec, 400 msec, 600 msec, . . . ), whilethe second network may use odd 100 msec intervals, (i.e., 100 msec, 300msec, 500 msec, . . . ), to poll its WTRUs. In this way, the twonetworks can avoid collisions and keep mutual interference low whilestill operating on the same frequency. This coordination may beperformed via broadcast messages or a direct signaling between the twonetworks, (e.g., via the RRM 500).

Polling is a coordinated process for controlling transmissions over awireless medium, as compared to contending for the medium upon need. TheHCF polls specific stations to see if they have something to transmitand then it allocates Tx time if they so request. In accordance with thepresent invention, coordinated polling is implemented between two HCFs.For mesh networks, most of the control is not centralized but ratherdistributed. Thus, two coordinated polling sequences, (i.e., from twodifferent coordinators, or from one coordinator to two differentnetworks), may be used to avoid interference between two networks. Inthis way, the two networks can avoid collisions and keep mutualinterference low while still operating on the same frequency. Thiscoordination may be performed via broadcast messages or a directsignaling between the two networks, (e.g., via the RRM 500).

As shown in FIG. 2, the present invention may be applied to multiplenetworks 200, 300 deployed concurrently in the same proximity, even ifthere is no direct communication between the networks. The networks 200,300 may be any type of networks including networks deployed underdifferent radio access technologies, (e.g., IEEE 802.11, IEEE 802.15,IEEE 802.16, cellular networks, or the like).

Where two or more networks 200,300, are deployed concurrently in closeproximity, the RRM 500 may run on all of the networks 200, 300. In suchcase, a hierarchy may be established for coordinating configurationchanges of the networks 200, 300, (such as changing frequencies), wherefor instance backhaul links (or highly loaded links) would takeprecedence over lightly loaded links.

A common RRM 500 may be provided across the networks 200, 300, or aseparate independent RRM 500 may be provided in each network 200, 300.For example, a common RRM 500 may be provided for IEEE 802.11 networksand IEEE 802.16 networks and for managing radio resources for thenetworks. The RRM 500 is not constrained to a single radio accesstechnology, but rather it can coordinate multiple wireless networks,even if they use different radio access technologies.

Coordination may be performed across networks deployed under differentradio access technologies, such as a cellular network and a wirelesslocal area network under IEEE 802.xx standards. For example, actions maybe performed by the RRM 500 to coordinate the load between two networks200, 300, using one radio access technology and to take the redundanciesof the network 400 that uses a different radio access technology intoaccount. These actions could include for example the forcing of a changeof channel, change of radio access technology, or the like, on specificWTRUs depending on the load conditions on all networks.

Although the features and elements of the present invention aredescribed in the preferred embodiments in particular combinations, eachfeature or element can be used alone without the other features andelements of the preferred embodiments or in various combinations with orwithout other features and elements of the present invention.

1. In a wireless network including a plurality of nodes and at least onewireless transmit/receive unit (WTRU), a method of managing radioresources in the wireless network, the method comprising: providing atleast one radio resource manager (RRM) in the wireless network; the RRMmonitoring performance of wireless communication links associated withthe nodes of the wireless network; and the RRM interacting with at leastone of the nodes to change a configuration on a particular one of thewireless communication links if performance on the particular wirelesscommunication link falls below an established threshold.
 2. The methodof claim 1 wherein each node provides a quality report to the RRM, thequality report including wireless backhaul link quality measurements andperformance statistics.
 3. The method of claim 1 wherein theconfiguration is changed by using at least one of a different frequencyband, a different time slot and a different frequency hopping pattern.4. The method of claim 1 wherein the backhaul network is configured in apoint-to-point or a point-to-multipoint topology.
 5. The method of claim1 wherein the backhaul network is configured in a mesh topology, eachnode being wirelessly connected to at least one neighboring node,whereby traffic may be routed one or more hops through the network. 6.The method of claim 1 wherein the configuration is changed to use two ormore links to accommodate load when a traffic load suddenly increases.7. The method of claim 1 wherein the RRM resides in one of the nodes ofthe wireless network.
 8. The method of claim 1 wherein the wirelessnetwork further includes an access router (AR) which provides access toan access network, the AR comprising the RRM.
 9. The method of claim 8wherein the access network is a wide area network (WAN).
 10. The methodof claim 9 wherein the WAN is the Internet.
 11. The method of claim 1wherein at least one of the nodes is an access point (AP).
 12. Themethod of claim 1 wherein the wireless network operates in time divisionmultiple access (TDMA), and the RRM assigns and reassigns timeslots as afunction of interference observed by the RRM in particular timeslots.13. The method of claim 1 wherein when the RRM recognizes that the WTRUis interfering with a wireless backhaul link between two of the nodes,the RRM interacts with at least one of the nodes to mitigate the impactof interference caused by the WTRU.
 14. The method of claim 13 whereinthe RRM changes an operating frequency on the wireless backhaul link.15. The method of claim 1 wherein the RRM changes a routing algorithmused to control traffic between at least two of the nodes.
 16. In awireless communication system including a plurality of wirelesscommunication networks operating in the same proximity, each networkincluding a plurality of nodes, a method of managing radio resources toavoid inter-network interference, the method comprising: providing atleast one radio resource manager (RRM) to coordinate resources among thenodes of each of the networks; the RRM monitoring performance onwireless communication links of the networks; and the RRM interactingwith at least one of the nodes to change a configuration on a particularone of the wireless communication links if performance on the particularwireless communication link falls below an established threshold. 17.The method of claim 16 wherein at least one node of one of the networksmonitors information broadcast by a source within another one of thenetworks to make better radio resource management decisions.
 18. Themethod of claim 17 wherein the broadcast information includes atimestamp reference.
 19. The method of claim 17 wherein the broadcastinformation includes a service indicator.
 20. The method of claim 17wherein the broadcast information includes a load indicator.
 21. Themethod of claim 17 wherein the broadcast information includes a pointcoordination function (PCF) polling frequency.
 22. The method of claim17 wherein the broadcast information includes frequency channels in use.23. The method of claim 17 wherein the broadcast information includesfrequency hopping patterns.
 24. The method of claim 17 wherein thebroadcast information includes power settings.
 25. In a wirelesscommunication system including a first wireless communication network, asecond wireless communication network located in the same proximity asthe first wireless communication network and a radio resource manager(RRM), each of the networks including a plurality of wirelesstransmit/receive units (WTRUs), a method of managing radio resources toavoid inter-network interference, the method comprising: the firstnetwork allowing the second network to initiate a polling process whilethe first network remains silent; and the first network initiating apolling process while the second network remains silent, wherein thefirst and second networks avoid collisions and keep mutual interferencelow while operating on the same frequency.
 26. The method of claim 25wherein the first network polls its WTRUs every even 100 millisecondintervals, and the second network polls its WTRUs every odd 100millisecond intervals.
 27. The method of claim 25 wherein the RRMcoordinates the first and second networks in time domain.
 28. The methodof claim 25 wherein the first and second networks have a contention freeperiod starting at substantially the same point in time.
 29. The methodof claim 25 wherein the first and second networks use different radioaccess technologies.
 30. A wireless network for managing radioresources, the network comprising: a plurality of nodes; at least onewireless transmit/receive unit (WTRU); and at least one radio resourcemanager (RRM), wherein the RRM monitors performance of wirelesscommunication links associated with the nodes of the wireless network,and the RRM interacts with at least one of the nodes to change aconfiguration on a particular one of the wireless communication links ifperformance on the particular wireless communication link falls below anestablished threshold.
 31. The network of claim 30 wherein each nodeprovides a quality report to the RRM, the quality report includingwireless backhaul link quality measurements and performance statistics.32. The network of claim 30 wherein the configuration is changed byusing at least one of a different frequency band, a different time slotand a different frequency hopping pattern.
 33. The network of claim 30wherein the backhaul network is configured in a point-to-point or apoint-to-multipoint topology.
 34. The network of claim 30 wherein thebackhaul network is configured in a mesh topology, each node beingwirelessly connected to at least one neighboring node, whereby trafficmay be routed one or more hops through the network.
 35. The network ofclaim 30 wherein the configuration is changed to use two or more linksto accommodate load when a traffic load suddenly increases.
 36. Thenetwork of claim 30 wherein the RRM resides in one of the nodes of thewireless network.
 37. The network of claim 30 wherein the wirelessnetwork further comprises: an access router (AR) which provides accessto an access network, the AR comprising the RRM.
 38. The network ofclaim 37 wherein the access network is a wide area network (WAN). 39.The network of claim 38 wherein the WAN is the Internet.
 40. The networkof claim 30 wherein the at least one of the nodes is an access point(AP).
 41. The network of claim 30 wherein the wireless network operatesin time division multiple access (TDMA), and the RRM assigns andreassigns timeslots as a function of interference observed by the RRM inparticular timeslots.
 42. The network of claim 30 wherein when the RRMrecognizes that the WTRU is interfering with a wireless backhaul linkbetween two of the nodes, the RRM interacts with at least one of thenodes to mitigate the impact of interference caused by the WTRU.
 43. Thenetwork of claim 42 wherein the RRM changes an operating frequency onthe wireless backhaul link.
 44. The network of claim 30 wherein the RRMchanges a routing algorithm used to control traffic between at least twoof the nodes.
 45. A wireless communication system for managing radioresources to avoid inter-network interference, the system comprising: aplurality of wireless communication networks operating in the sameproximity, each network including a plurality of nodes; and at least oneradio resource manager (RRM) for coordinating resources among the nodesof each of the networks, wherein the RRM monitors performance onwireless communication links of the networks, and the RRM interacts withat least one of the nodes to change a configuration on a particular oneof the wireless communication links if performance on the particularwireless communication link falls below an established threshold. 46.The system of claim 45 wherein at least one node of one of the networksmonitors information broadcast by a source within another one of thenetworks to make better radio resource management decisions.
 47. Thesystem of claim 46 wherein the broadcast information includes atimestamp reference.
 48. The system of claim 46 wherein the broadcastinformation includes a service indicator.
 49. The system of claim 46wherein the broadcast information includes a load indicator.
 50. Thesystem of claim 46 wherein the broadcast information includes a pointcoordination function (PCF) polling frequency.
 51. The system of claim46 wherein the broadcast information includes frequency channels in use.52. The system of claim 46 wherein the broadcast information includesfrequency hopping patterns.
 53. The system of claim 46 wherein thebroadcast information includes power settings.
 54. A wirelesscommunication system for managing radio resources to avoid inter-networkinterference, the system comprising: a first wireless communicationnetwork including a plurality of wireless transmit/receive units(WTRUs); a second wireless communication network located in the sameproximity as the first wireless communication network, the secondwireless communication network including a plurality of WTRUs; and atleast one radio resource manager (RRM), wherein the first network allowsthe second network to initiate a polling process while the first networkremains silent, and the first network initiates a polling process whilethe second network remains silent such that the first and secondnetworks avoid collisions and keep mutual interference low whileoperating on the same frequency.
 55. The system of claim 54 wherein thefirst network polls its WTRUs every even 100 millisecond intervals, andthe second network polls its WTRUs every odd 100 millisecond intervals.56. The system of claim 54 wherein the RRM coordinates the first andsecond networks in time domain.
 57. The system of claim 54 wherein thefirst and second networks have a contention free period starting atsubstantially the same point in time.
 58. The system of claim 54 whereinthe first and second networks use different radio access technologies.